Lusitania was sunk without a warning, killing over 120 Americans. One year later, the Sussex was sunk by German U-boats and American citizens were outraged at these direct violations of their neutral rights at sea. At this point, a small percentage of Americans, including presidential hopeful Teddy Roosevelt, demanded “immediate warfare. ” In 1916 President Wilson took a stronger stance toward foreign affairs by increasing the size of the military and issuing a warning to the Germans:
Unless the Imperial Government should now immediately declare and effect an abandonment of its present methods of submarine warfare against passenger and freight-carrying vessels, the Government of the United States can have no choice but to sever diplomatic relations with the German Empire altogether (1). The Germans responded by temporally ceasing submarine warfare until 1917 when German Ambassador Berstorff announced the continuation of submarine warfare and ended diplomatic relations with the United States. However, military strategists predicted certain defeat for the Germans if America entered the war at this point.
In an attempt to eliminate the threat of American involvement in Europe, Foreign Minister Alfred Zimmerman attempted to provoke Mexico and Japan into attacking the United States with the promise of German assistance after the European front was conquered. A message containing Zimmerman’s intent was decoded by the British and sent to the US, further swaying Americans to action. Due primarily to submarine warfare and the Zimmerman note, President Wilson asked Congress for permission to go to war, and on April 6, 1917, congress officially declared it.
President Wilson, along with many Americans, justified their involvement as “an act of high principle and idealism as a crusade to make the world safe for democracy. ” (2) While these are some of the main events, there are many other theories regarding why the US entered into World War I. Some propose that the US was never actually neutral, but had been supporting the British; this thinking gives a different light on the events of submarine warfare with the Germans.
The high infiltration of Pro-British propaganda as well as the considerable profits to the hurting economy lead some to believe that it would have been impossible for the US to remain neutral and not engage in the war. Others propose that as German forces crept into the Atlantic and threatened to conquer Britain, the US felt that its defenses and the country’s security were threatened, again justifying involvement in the war. In all practicality, it is impossible to pinpoint the entry of the United States to a number of certain events and it was most definitely a combination of many factors. The most important of these events are discussed above, explaining why the United States entered World War I.